Conventional 3-point seatbelt systems typically include both a lap belt and a shoulder belt which are simultaneously drawn across a seat occupant and attached to a buckle mounted adjacent the seat. The lap belt and shoulder belt are typically formed from a single loop of web that is divided into the two belt sections by a buckle tongue that is attached to the buckle. One end of this web is typically fixed to an anchor point on the floor of the vehicle opposite the buckle, and the other end is typically wound onto a spring-loaded retractor that maintains tension in the web when in use and retracts the web when not in use. The retractor can be mounted to the floor opposite the buckle, or it can be mounted to an interior wall of the vehicle adjacent to the seat. The web typically extends upward from the retractor and through a D-ring or other guide feature mounted to the interior wall, and then diagonally downward across the seat to form the shoulder portion of the seatbelt. The web then passes through the tongue and back across the seat to the anchor point to form the lap portion of the seatbelt.
The buckle tongue on conventional 3-point seatbelt systems is typically able to slide up and down on the web. This makes the seatbelt easy to put on or take off, and enables the retractor to maintain a comfortable level of tension in the seatbelt during use. This feature also allows the retractor to fully retract the unbuckled seatbelt without the buckle tongue becoming hung up on the D-ring.
Although allowing the buckle tongue to slide on the web may be advantageous during routine use, it may also be desirable to lock the buckle tongue on the web during a rough ride, impact or crash to prevent the web from passing through the tongue and loosening, for example, the lap belt during such an event. Conventional buckle tongues typically rely on constant tension in the lap belt to remain locked on the web. In a vehicle that typically experiences rough riding conditions, (e.g., such as an off road vehicle (ORV) or a recreational utility vehicle (RUV)), however, the loads in the lap belt tend to vary as the occupant jostles around, and as a result there will be little or no tension in the belt at times. If tension is momentarily lost, the buckle tongue will momentarily unlock and allow a small amount of web to pass through the buckle tongue before the subsequent tension in the belt relocks the tongue on the web. As a result of the varying tension, the belt may creep through the buckle tongue and inadvertently loosen on the occupant. Accordingly, it would be advantageous to provide a buckle tongue for use with a 3-point seatbelt system that reduces or eliminates belt creep under rough riding conditions.